US2310119A - Extensible ladder - Google Patents

Description

J. P. REINHARDT EXTEN Feb. 2, 1943.

SIBLE LADDER Filed Jan. 20, 1942 3 Sheets-Sheet 1 INVENTOR.

JOHN RE/NHARDT 06, 12 ATTORNE Y Feb 2, 1943. REiNHARDT 2,310,119

EXTENSIBLE LADDER Filed Jan. 20, 1942 3 Sheets-Sheet 2 INVENTOR.

JOHN RE/NHARDT I Y I v ATTORNEY Feb. 2, 1943. J. P. REINHARDT EXTENS IBLE LADDER s Sheeis-Sheet 5 .Filed Jan. 20, 1942 INVENTOR.

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a N T R m w A .T H A m E R W o J Patented Feb. 2, 1943 UNITED STATES PATENT OFFICE EXTENSIBLE LADDER- John P. Reinhardt, Brooklyn, N. Y.

Application January 20, 1942, Serial No. 427,455

15 Claims.

This invention relates to extensible ladders. It is particularly directed'to a ladder which may be used in schools, courtroomsor auditorium, for

replacing burnt out lamps on the ceiling, or fordivers other purposes.

An object of this invention is to provide a ladder of the character described,- comprising a base havingv spaced legs to straddle chairs. benches, or seats, the legs of the ladder being adapted to move between'the rows of benches or seats.

A further object of this invention is to provide a ladder of the character described, having a platform on the top extension or section, and a railing mounted on the platform, said railing being removable from the platform, and the base of said ladder being provided with means to supportthe railing between the legsthereof.

Still a further object of this invention is to provide a ladder of the character described, having an outrigger to aid in supporting the ladder against tilting, and also having means to keep the ladder from rolling when in use.

Another object of this invention is to provide an extensible ladder of the character described, comprising a base and aplurality of extensible, telescoping sections, said base and each section comprising two pair of aligned, vertical corner members, rigidly interconnected and serving as a guide for an adjacent section or sections slidable relative thereto, means being further provided to limit relative movement between adjacent sec-,

manipulate, smooth and positive in action, and

yet. practical and eificient to a high degree.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

The invention accordingly consists in the features' of construction, combinations of elements. and arrangement of parts which will be exemplifled in the construction hereinafter described, and of which the scope of application will beindicated in the following claims.

In the accompanying drawings, in which is shown one of the various possible illustrative embodiments of this invention,

Fig. l is a front elevational view of the ladder in extended position;

Fig. 2 is a side elevational view thereof;

Fig. 3 is anenlarged, side elevational view of the platform and railing therefor;

Fig. 4 isa cross-sectional view taken on line 4w of Fig.3;

Fig. 5 is a sideelevational view of the ladder in collapsed condition;

Fig. 6 is a front elevational view of the ladder in collapsed condition;

Fig. '7 is a cross-sectional view taken on line 1-1 of Fig. 5;

Fig 8 is a cross-sectional view taken on line 8-43 of Fig. 7; and

Fig. 9'is'a cross-sectional View taken on line 99 of Fig. 7.

Referring. now in detailto the drawing, Ii] designates a ladder embodying the invention. The ladder comprises generally of a base II and a plurality of ladder extensions I 2, l3 and M. Section l4 carries a platform [5 at its-upper end, onwhich isremovably mounted a railing member Hi;

The support 'or base H comprises a pair of vertical front, posts or pipes ll interconnected by a plurality 'ofrungs 1-9. Fixed to the lower ends of vertical side members I1; is a horizontal channel shaped member 20. Fixed to the underside of the channel shaped member an, are a pair of spaced swivel wheels 22. Therungs l9 may comprise metal bars welded at the ends thereof to the vertical hollow posts or side members ll.

Fixed to the. posts I! are a pair of similar members. 23 disposed in parallel planes, likewise madeof hollow metal pipe, each having a vertical portion 24, parallel to member H, and a portion 25 included upwardly and forwardly from the upper end of portion 24. The upper ends of portions 25are welded or otherwise fixed torside members I? at points below the upper ends thereof. interconnecting side members ll with substantially the upper ends of portions 24 of It- Will'be noted'that said pipes H, 23; 3B, 3

Members 23 may be interconnected by are welded or otherwise secured together to form a strong rigid support for the ladder.

Fixed to the lower ends of portions 24 of members 23, is also a horizontal channel shaped member 35, similar and parallel to the channel shaped member 28. Fixed to the ends of channel shaped member 35, is also a pair of swivel wheels 36. Mounted on the top of the channel shaped member 35 is a metal box 31 filled with lead, as at 38, forming a counterweight to prevent tilting of-the ladder.

The box 31 has horizontal, outwardly extending flanges 39 at its upper end formed with through openings 46. The top wall of channel shaped member 35 is formed with screw threaded openings 4| aligned with openings 40. Extending through the openings 48, and screwed within the openings M are screws 42 adapted to contact the floor, to prevent rolling or movement of the ladder when in use. Thus, when the ladder is in position for use, the screws 42 may be rotated until the lower ends thereof press against the floor to prevent rolling of the ladder.

Welded or otherwise fastened to the insides of the upper ends of side members I1 and 23, are parallel, vertical plates 44. The upper rear corners of plates are interconnected by a horizontal transverse pipe 45, for the purpose hereinafter appearing. Pipe 45 is located substantially at the level of the upper ends of posts [1. Plates 44 extend to somewhat below the upper ends of members 23.

There is furthermore welded, or otherwise secured, to the inner sides of posts I! and members 30, a pair of vertical, parallel plates 46, having the same width as plates 44. The lower edges of plates 46 are substantially at the level of the pipes 36. The plates 44 and 46 are spaced from one another, as shown in Fig. of the drawings.

Welded, or otherwise secured, to the inner surfaces of plates 44 and 46, adjacent the front and rear edges thereof, are pairs of vertical angle shaped guide members 48 and 49 extending from the upper ends of plates 44 to substantially the lower ends of plates 46. The pair of members 48 are aligned with the pair of members 49. The members 49 have walls 49a extending toward each other; and members 48 likewise have 48a extending inwardly toward each other. Members 48 furthermore have walls orflanges 48b extending towards members 49; and members 49 have walls or flanges 4%, extending towards members 48. Thus, the members 48 and 49 constitute vertical corner guide pieces fixed to the base or frame and rigid therewith in which section I2 telescopes.

Section I2 comprises two pairs of similar, symmetrically disposed, vertical, Z-shaped members 50 and 5| slidably engaging the angle shaped members 48 and 49, respectively. Z-shaped members 58 have walls 58a contacting the inner interconnected by transverse horizontal metal strips 52, welded or otherwise secured to the walls 58?) thereof. Members 5| .are'interconnected by transverse horizontal metalstrips 53; welded, or otherwise secured, to walls 5| b thereof. The members 56, 5| atthe rear of section I2 are interconnected by transverse members 52a welded, 751

walls 5Ic of members 5|.

or otherwise secured to walls 566, 5Ic thereof. Members 50, 5| at the front of the ladder are connected by horizontal rungs 54.

It will be noted that section I2 is substantially the same height as the post I! and rests on channel sloped member 28 when the ladder is collapsed. Members 58, 5| at the front of section I2 are interconnected by a transverse horizontal angle shaped member 55 on the central portion of which is mounted an upwardly extending pulley 56, for the purpose hereinafter appearing. The upper ends of members 50, 5| of sections I2 are interconnected by a transverse member 55a, on the central portion of which is mounted a downwardly extending pulley 56a, for the purpose hereinafter appearing.

It will now be understood that section I2 may slidably move up and down, being guided by members 48 and 49 of the base.

Means is provided to limit upward movement of ladder section I2. To this end, there is fixed to the posts I! below the upper ends of said posts, a pair of inwardly extending stop members 60. Fixed to the ends of the lowermost rung 54 of section I2 are a pair of stop members 6| adapted to contact the stops when the ladder I2 has been moved upwardly. It will be understood that when the stops 69, 6| contact, section I2 overlaps the upper end of base I I to a considerable extent, so as to prevent swaying of section I2.

Section I3 is telescoped within section I2, and is of the same length as said section. It comprises pairs of similar, symmetrically disposed Z-shaped corner members 63 and 64 of the same length as'posts Il guided by Z-shaped members 58 and 5| of section I2. Members 63 comprise walls 63acontacting walls 500 of members 50, and walls 631) extending inwardly therefrom, and walls 630 extending towards the members 64.

Members 64 comprise walls 64a contacting Walls 64b extend in wardly toward each other, and walls 640 extend towards members 63. Members 63 are interconnected by horizontal, transverse strips 65, welded, or otherwise secured, to walls 63b thereof. Members 64 are interconnected by horizontal, transverse strips 66, welded, or otherwise secured, to walls 64b thereof. The members 63, 64 at the front of section I3 are interconnected by rungs 61 spaced apart the same as the rungs 54 and I9.

Members 63, 64 at the rear of section I3 are interconnected by horizontal, transverse strips 65a, welded, or otherwise secured, to walls 630, 64c thereof.

The lower ends of the members 63, 64 at the rear of section I3, are interconnected by a transverse member 68, on the mid portion of which is an upwardly extending pulley 69. The upper ends of the sections 63, 64, at the rear of section I3, are interconnected by a transverse horizontal member I 8, on the central portion of which there is mounted a downwardly extending pulley 1|, for the purpose hereinafter appearing.

Section I3 also rests on channel 26 when the ladder is collapsed.

Means is provided to limit movement of section I3 relative to section I2. To this end, there is fixed to members 59, 5| at the front of section I2, at points spaced from the upper ends thereof, stop members I2. Fixed to the ends of the lowermost rung 67 of section I3 are stop members 13 adapted to contact the stop members I2 to limit upward movement of section I3, relative to section I2.

It will be noted that the stop members I2 are as considerable: distance: below the; upper; end; of. section: l'z-lsorthat sections. [3: overlap section: I 2 in:v its extended; position, to prevent. swaying, of section I 37Wh811 extended.

Section M-is telescoped.withinisectionI31. Said section: I 4 comprises pairs of 1 similar; symmetrically-disposed, angle shapedmembersJS and-16. Angle. shaped members 15' comprise. walls. 15a. contacting, walls 6300f member '63; and .walls 15b extending. inwardlytoward. each: other; Member.-

16- comprises walls 16a. contacting wall 640: of?

member 64,, and walls. 16b. extending: inwardly toward. each other; Members 15iare;intercon.- nected by transverse, ,,horizontal.fstrips: l8, welded, orotherwise-secured; to walls:15lr thereof; Mem

bers 1.1 6 are interconnectedby transverse, horizontal strips 19; welded; .orotherwise secured; to walls 16b thereof; The memhersrlfi, .16 atzthe, frontzof' section Id-iarecint'erconnectedfby rungs 11;. Meme bers 15,16 at the: rearofv section are intercomnectedgby horizontal, transverse strips '|8a,..we1ded, or otherwise secured, towa'lls: 15a; 'lfiai'thereofi The;members;l8,-.|9i at the lower end of section I4: are interconnected" by a horizontaliangle shaped'member 30, forthe purpose hereinafter appearing."

Means is provided; to: limitupward: movement: of section |4=relative.to:section1 13; To this end, there is fixed to members 63; 64Zatthe frontof.

section; l3; a considerable distance: below the upper: endsthereof, stop membersfll. Fixed to the ends of thelowermostrungz'l'l' of section. M, are stops 82-, adaptedzto contact stops. SJ, to.. limit upward. movement. of section I4 relativetoseetion I32 Fixed to the central. portion of pipe45isaiorwardly extending. pulley 45a; Mounted. on the membersSZ; 33; is a winch 83 adaptedto be operatedby acrank handle 8.4. The rope R from the winch 83 is passedover pulley-45a, then around under pulley 56. then: around overpulley 56a, then" around under pulley: 69, then. around over pulley Tl, andwisitied. t'o the mid-portion ofamember 80,- as showninFig; 8 oftherdrawings.

Thus, when the-winchisturned', the rope R will first cause section l'41to;move upwardly relativetosectional3=y Then sections 13 and l4.moveupwardly togetherrelativeto section I2, and then sections I2; l3 and M: move upwardly together, relative to the base.

The platform I5 is" fixed to theupper end of section I4". Said. platform comprises; an angle shaped;.horizontal, rectangular frame 90, having inwardly extending, horizontal flanges and up.- wardly extending; vertical. flanges, and. supportinga board' or floor 9.1. Fixed-touthe. cornersof the frame" 911: are. vertical. sleeves 92.. Welded to the underside of the frame 90, are a pair: of parallel, transverse, angle shaped members 93, having downwardly extending fianges'lii. The upperend ofthesection. 1 dis welded to flanges 94;- closer When the; ladder isnot. in use; the; railing. l6: maybe removed, and hung: on apairior hooks.

I; fixed. to. one: of the" members: 39:,v and: disengageably engaged. by a swinging.- hook. l0] mounted; on' the other member; 3.0;

Outrigger-means may be provided, to aid insupporting the ladder; To this end; the posts I 1 are formed with aligned slotted'ears- I05: Pivoted'to the: slotted ears I are downwardly, outwardly and: forwardly inclined'mem-bers 1061 supported on-swivel wheels I111. The outer ends of. member. 20- are interconnected to'the; lower ends of members I06 by connecting rods IOB'in; which there is interposed turnbuckles I09. The: outrigger: maybe detached from'the. ladder'when desired.

Itwillthuszbe-see'n thatthereis provided a deviceini which the'several objects of this:invention are achieved, and which is well adapted to. meet theconditions :of practical use;

As various: possible embodiments might be made of the above invention; and as various changes might be made in the'embodiment above set: forth, it is to be understood that all matter herein set forth or shown in. the accompanying drawings is to be interpreted as illustrative and not ina limiting; sense.

Having thus described my invention,,I claim as new and desire to secure by Letters Patent:

1. A ladder comprising a base having frontand rear legs, and means above the lower ends of said legs interconnecting said legs, whereby said laddermay straddle benches, the front of said base being provided; with a plurality of rungs, an extensible ladder section slidably. mounted on'said base. and" provided. with a plurality of rungs, a

winch passing around the pulley on the base, and: beneath the pulley at the lower end of the first extensible. section, and over the. pulley at the upper end of the first extensible'section, andaround the pulley'at'the lower'endofthe-second extensiblesection and. around the pulley at the upper end of. the second extensible section, said rope being-attached to the lower end of the third extensible section, said rope, pulley and winch being. located substantially centrally of the ladder between the'sides thereof.

2. An. extensible ladder comprising a base, a plurality of rungs-on the base; two pair of vertical; aligned, angle shaped guide members fixed to said base, one pair of angle shaped members:

being: aligned with the other pair of angle shaped membersan extensible section telescoped within saidiangular guide members, and comprising two pair of Z-shaped members, one pair of Z-shaped members being aligned with the other pair ofZ shaped. members, one pairof Z-shaped members slidably engaging one pair of angle shaped members' and the other pair of Z-shaped members sliclably. engaging the other pair of angle shaped members, transverse members interconnecting each p'airofzeshaped members, and rungs interfront of cal, aligned. angle shaped; guide members-fixed to said base, one pair of angle shaped members being aligned with'the other pair of angle shaped members, an extensible section telescoped within said angular guide members, and comprising two pair of Z-shaped members, one pair of- Z-shaped members being aligned with the other pair of Z- shaped members, one pair of Z-shaped members slidably engaging one pair of angle shaped members and the other pair of Z-shaped members slidably engaging the other pair of angle shaped members, transverse members interconnecting each pair of Z-shaped members, rungs interconnecting the Z-shaped members at the front of said extensible sections, and means to limit relative movement between said extensible section and said base.

4. An extensible ladder comprising a base, a plurality of rungs on the base, two pair of vertical, aligned, angle shaped guide members fixed to said base, one pair of angle-shaped members being aligned with the other pair of angle shaped members, an extensible section telescoped within said angular guide members, and comprising two pair of Z-shaped members, one pair of Z-shaped members being aligned with the other pair of Z- shaped members, one pair of Z-shaped members slidably engaging one pair of angle shaped members and the other pair of Z-shaped members slidably engaging the other pair of angle shaped members, transverse members interconnecting each pair of Z-shaped members, rungs interconnecting the Z-shaped members at the front of said extensible sections, means to limit relative movement between said extensible section and said base, a second extensible section telescoped within the first extensible section and comprising a pair of vertical Z-shaped members slidably engaging a pair of Z-shaped members of the first extensible section, and a second pair of Z-shaped members slidably engaging the other pair of Z- shaped members of the first extensible section, transverse members interconnecting each pair of Z-shaped members of the second extensible section, and rungs interconnecting the Z-shaped members at the front of the second extensible section.

5. An extensible ladder comprising a base, a plurality of rungs on the base, two pair of vertical, aligned, angle shaped guide members fixed to said base, one pair of angle-shaped members being aligned with the other pair of angle shaped members, an extensible section telescoped within said angular guide members, and comprising two pair of Z-shaped memb'ers, one pair of Z-shaped members being aligned with the other pair of Z- shaped members, one pair of Z-shaped members slidably engaging one pair of angle shaped members and the other pair of Z-shaped members slidably engaging the other pair of angle shaped members, transverse members interconnecting each pair of Z-shaped members, rungs interconnecting the Z-shaped members atthe front of said extensible sections, means to limit relative movement between said extensible section and said base, a second extensible section telescoped within the first extensible section and comprising a pair of vertical Z-shaped members slidably engaging a pair of Z-shaped members of the first extensible section, a second pair of Z-shaped members slidably engaging the other pair of Z- shaped members of the first extensible section, transverse members interconnecting each pair of Z-shaped members of the second extensible section, rungs interconnecting the Z-shaped members at the front of the second extensible section,

and a third extensible section telescoped within thesecond extensible section and comprising two pair of vertical-angle shaped members, one pair of angle shaped members slidably'engaging a pair of Z-shaped members of the second extensible section, and the other pair of angle shaped members of the third extensible section slidably engaging the other pair of Z-shaped members of the second extensible section, transverse members interconnecting each pair of angle shaped members of the third extensible section, and rungs interconnecting the angle shaped members at the front of the third extensible section.

6. An extensible ladder comprising a base, a plurality of rungs on the base, two pair of vertical, aligned, angle shaped guide members fixed to said base, one pair of angle shaped members being aligned with the other pair of angle shaped members, an extensible section telescoped within said angular guide members, and comprising two pair of Z-shaped members, one pair of Z-shaped members being aligned with the other pair of Z- shaped members, one pair of Z-shaped members slidably engaging one pair of angle shaped members and the other pair of Z-shaped members slidably engaging the other pair of angle shaped members, transverse members interconnecting each pair of Z-shaped members, lungs interconnecting the Z-shaped members at the front of said extensible sections, means to limit relative movement between said extensible section and said base, a second extensible section telescoped within the first extensible section and comprising a pair of vertical Z-shaped members slidably engaging a pair of Z-shaped members of the first extensible section, a second pair of Z-shaped members slidably engaging the other pair of Z- shaped members of the first extensible section, transverse members interconnecting each pair of Z-shaped members of the second extensible section, rungs interconnecting'the Z-shaped members at the front of the second extensible section, a third extensible section telescoped within the second extensible section and comprising two pair of vertical angle shaped members, one pair of angle shaped members slidably engaging a pair of Z-shaped members of the second extensible section, and the other pair of angle shaped members of the third extensible section slidably en gaging the other pair of Z-shaped members of the second extensible section, transverse members interconnecting each pair of angle shaped members of the third extensible section, rungs interconnecting the angle shaped members at the 1 front of the third extensible section, and a platform mounted on the upper end of the third extensible section, and a removable railing on said platform.

7. A ladder comprising a base having front and rear vertical leg portions, and a horizontal interconnecting portion, spaced suificiently above the lower ends of said legs whereby said ladder may straddle a bench, telescoping extensible ladder sections slidably mounted on the front leg portion, a winch on said base, a counterweight mounted on the rear leg portion, pulleys on said base and sections, and a single rope operated by said winch to extend said sections, said pulleys, rope and winch being located substantially centrfally of said ladder and between the sides there- 0 8. A ladder comprising a base having front and rear vertical leg portions, and a horizontal inter connecting portion, spaced well above the lower ends of said legs whereby said ladder may straddle a bench, an extensible ladder section slidably mounted on the front leg portion, a. counterweight mounted on the rear leg portion, said front and rear leg portions being supported on swivel wheels, and an outrigger attached to the front leg portion of the base and extending forwardly and outwardly therefrom and engaging the floor to aid in preventing tilting of the ladder.

9. A ladder comprising a base having front and rear vertical leg portions, and a horizontal interconnecting portion, spaced above the lower ends of said legs, an extensible ladder section slidably mounted on the front leg portion, a counter weight mounted on the rear leg portion, said front and rear leg portions being supported on swivel wheels, means on the base adapted to engage the fioor to prevent rolling of the ladder, and an outrigger attached to the front leg portion of the base, and extending forwardly and outwardly therefrom, and engaging the floor to prevent tilting of the ladder.

10. An extensible ladder comprising a base having spaced front and rear legs, means interconnecting the front and rear legs, said interconnecting means being located a substantial distance above the lower ends of the legs and forming a space below said interconnecting means and between said legs to straddle furniture, a counterweight on the rear legs, and a plurality of telescoping extensible ladders on the base ad- J'acent the front legs.

11. An extensible ladder comprising a base having spaced front and rear legs, means interconnecting said legs, substantially above the lower ends of said legs, a counterweight on the rear legs, a plurality of telescoping extensible ladders on the base adjacent the front legs, means to limit relative movement between adjacent extensible sections and between one of the sections and the base, a platform fixed to the uppermost extensible sections, a railing removably mounted on said platform, and means on the base to dependingly support said railing when removed from said platform, between the front and rear legs and below said interconnecting means.

12. An extensible ladder comprising a base having a vertical front leg, a vertical rear leg, and a horizontal member interconnecting the upper end of the rear leg with a portion of the front leg, and an inclined member interconnecting the rear leg with an upper portion of the front leg, said ladder having a space below the interconnecting portion and between said front and rear legs, sulficient to permit the ladder to straddle benches and the like furniture, and a plurality of extensible sections on the front leg of said base.

13. An extensible ladder comprising a base having a vertical front leg, a vertical rear leg, and a horizontal member interconnecting the upper end of the rear leg with a portion of the front leg, and an inclined member interconnecting the rear leg with an upper portion of the front leg, said ladder having a space below the interconnecting portion and between said front and rear legs, sufficient to permit the ladder to straddle benches and the like furniture, and a plurality of extensible sections on the front leg of said base, said base having a plurality of rungs, and said extensible sections being telescoped and each having two pairs of aligned corner members, the front corner members being interconnected by horizontal rungs.

14. An extensible ladder comprising a base,

of said section, including rungs at the front of said section,- asecond extensible section telescoped within the first extensible section, and

having two pairs of vertical corner guide members engaging the vertical guide members of said first extensible section, means to rigidly interconnect the guide members of said second section, including rungs at the front of said section, a third extensible section telescoped within said second extensible section and comprising two pairs of vertical guide members engaging the guide members of said second section, means to rigidly interconnect the guide members of said third section, including rungs at the front of said third section, a platform at the upper end of said third extensible section, a winch on said base, a pulley at the upper end of said base, a pulley at the lower end of said first extensible section, a pulley at the upper end of said first extensible section, a pulley at the lower end of said second extensible section, a pulley at the upper end of said second extensible section, and a rope extending from the winch around the pulley at the upper end of the base, around the pulley at the lower end of the first extensible section, around the pulley at the upper end of the first extensible section, around the pulley at the lower end of the second extensible section, around the pulley at the upper end of the second extensible section, and being attached to the lower end of the third extensible section, said ladder comprising a pair of spaced front and rear vertical legs, said extensible sections being mounted on the front leg of said ladder, a member interconnecting the front and rear legs and disposed above the lower ends of said legs, said ladder having a space below said last interconnecting means and between said legs, to permit the ladder to straddle benches and the like furniture.

15. An extensible ladder comprising a base, rungs at the front of the base, two pairs of parallel, vertical, aligned, corner guide members fixed to said base, an extensible section slidably mounted within said guide members, and having two pairs of vertical corner guide members engaging said first pair of corner guide members, means to rigidly interconnect the guide members of said section, including rungs at the front of said section, a second extensible section telescoped within the first extensible section, and having two pairs of vertical corner guide members engaging the vertical guide members of said first extensible section, means to rigidly interconnect the guide members of said second section, including rungs at the front of said section, a third extensible section telescoped within said second extensible section and comprising two pairs of vertical guide members engaging the guide members of said second section, means to rigidly interconnect the guide members of said third section, including rungs at the front of said third section, a platform at the upper end of said third extensible section, a winch on said base, a pulley at the upper end of said base, a pulley at the lower end of said first extensible section, a pulley at the upper end of said first extensible section, a pulley at the lower end of said second extensible section, a pulley at the upper end of said second extensible section, and a rope extending from the winch around the pulley at the upper end of the base, around the pulley at thelower end of the first extensible section, around the pulley at the upper end of the first extensible section, around the pulley at the lower end of the second extensible section, around the pulley at the upper end of the second extensible section, and being attached to the lower end of the third extensible section, said ladder comprising a pair of spaced 10

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